<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    //执行上下文：js代码执行的环境
    let name='tom';
    function fn1(){
        let age =10;
        function fn2(){
            let sex='男';
            console.log(name);
            console.log(age);
            console.log(sex);
        }
        fn2();
    }
</script>
</html>